Abstract Background The wearable cardioverter-defibrillator (WCD) is a temporary treatment option for patients at high risk for sudden cardiac death (SCD) and/or for patients in whom implantation of a cardioverter defibrillator (ICD) is temporarily not possible. Purpose To investigate incidence and predictors of appropriate WCD shocks. Methods We performed a retrospective analysis of all patients with appropriate shocks delivered by a WCD in the cohort of the Austrian WCD registry between 2010 and 2018. Within this dataset, we identified predictors within the baseline characteristics, the indication for the WCD and preceding alarms automatically recorded by the WCD. Results: Baseline Within 879 registered in the Austrian WCD registry, 31 patients (3,5%) received appropriate WCD shocks due to ventricular tachycardia (VT) or ventricular fibrillation (VF). Compared to the total cohort, shocked patients were elder (mean age 67 ± 14 vs. 60 ± 14 years, p = 0,001) and the percentage of female patients was lower (11% vs. 21%, p = 0,262). The mean baseline LVEF at prescription was 33 ± 15% in the population with appropriate shocks compared to 32 ± 14% in the all-over cohort (p = ns). In the Austrian WCD population, 378/879 patients had a WCD due to secondary prevention. Within this cohort 5,6% (21/378) had shocks for VT/VF again, compared to 10/501 (2%) shocked patients in the primary prevention cohort. 31/879 (3.5%) patients received 57 appropriate shocks, the per patient shock rate was 2 [1;5]. These shocks were induced by 25 ventricular tachycardia and 26 times ventricular fibrillation. The octagenarians with 11% (7/34) shocked patients, showed a significant higher likelihood to receive shocks (p = 0,008) as well as the cohort of secondary preventive prescribed WCD-patients (p = 0,007). There were more shocks in patients, when prescribed with a WCD due to ICD associated infections (p = 0,001), when used as a bridge to ICD (p = 0,042) and in patients with ongoing risk stratification (p = 0,009). Looking through the automatically recorded alarms preceding a WCD shock, shocked patients experienced significantly more often non sustained VTs (p < 0,0005) and sustained VTs that were haemodynamically tolerated and did not require a treatment (p < 0,0005). Conclusion The WCD is effective in preventing SCD and an important risk stratification tool. We identified advanced age, patients with either already confirmed indication for ICD implantation (either temporary contraindication for implantation or temporary explantation) or risk stratification of an unclear cardiomyopathy, the cohort of secondary prevention and preceding nsVTs and stable VTs as predictors for appropriate WCD therapies.

Abstract Background The wearable cardioverter-defibrillator (WCD) is a treatment option for patients at high risk for ventricular arrhythmia, either if the risk is potentially reversible or if an implantable cardioverter defibrillator (ICD) implantation is currently not possible. Methods We performed a retrospective analysis of all alarms in the cohort of the Austrian WCD registry between 2010 and 2018. Type of arrhythmias was assessed by independent review of two cardiologists. Results 25.540 automatically recorded ECGs in 605 patients (68%) were analyzed. 1125 ECGs showed sustained ventricular arrhythmias in 117 patients, 65 ECGs showed non sustained VTs. 24.415 ECGs in 488 patients showed inadequate alarms Reasons for inadequate alarms were artefacts (97%), pacemaker or t-wave oversensing (0,3%) and in 2,3% atrial fibrillation or SVTs. 5860 manually recorded ECGs in 608 patients (68%) were analyzed. 298 (5%) of these ECGs showed following arrhythmias: atrial fibrillation (34,7%), SVTs (28%), sinustachycardia (10,7%), non sustained VTs (12%) and sustained VTs or sustained slow VTs (6,7%), premature ventricular beats or bradycardia was identified in 8%. The remaining 5562 ECGs (95%) showed normal sinus rhythm. Of the 895 patients (60±14 years, 20% female), 34 (3,8%) received a total of 65 automatically triggered shocks (median 2; range 1–5). 31/895 (3.5%) patients received 57 appropriate shocks (median 1, range 1–5) for 49 arrhythmic events, whereas 7/895 (0.8%) patients received 8 inappropriate shocks (median 1, range 1–2). 44 events were successfully terminated with the first shock (85,7%) and 4 events were terminated with the second shock. In one patient, a shock treatment for VF was not successful. The time from event onset to shock was median 60 [40; 1187] sec. The median time from WCD prescription to a shock event was 8 days [1–151]. 23/ 34 patients (68%) received their first WCD shock within 30 days. Seven patients (0.8%) received a total of nine inappropriate shocks due to different reasons: artefacts (2 inappropriate shocks), non-shockable rhythms (asystole, weak action, 3 shocks) and atrial fibrillation with a bundle branch block in two cases. In one patient VF terminated spontaneously before the WCD treatment was delivered. Conclusion The WCD is an effective treatment option in patients with a high SCD risk but it also triggers a significant amount of alarms. Although many inadequate alarms occurred, adequate alarms led to arrhythmia detection such as in VT/VF events which were successfully terminated by the WCD in 3,4% of patients.

Background: Under normoxic conditions, the predominant energy metabolism of healthy cardiac cells is based on beta-oxidation of free fatty acids.Under severe myocardial hypoxia, ischemic heart cells switch their energy gain from beta-oxidation to glucose metabolism to increase ATP production per oxygen molecule.This metabolic pathway appears as perfusion-metabolism mismatch in 18F-fluorodeoxyglucose (18F-FDG) PET images, as increased 18F-FDG uptake in underperfused hypoxic myocardial areas.The aim of our study was to evaluate simultaneous perfusion, metabolism and function of the ischemic heart by hybrid 18F-FDG-PET-cMRI with late enhancement images in a translation animal model of heart failure to 1) elaborate the underlying molecular mechanisms of perfusion-metabolism mismatch, and 2) evaluate the predictive value of 18F-FDG-PET-cMRI in development of ischemiatriggered left ventricular dysfunction.Methods: Closed-chest reperfused acute myocardial infarction (AMI) was induced in 36 domestic pigs by 90 min occlusion of the mid left anterior descending artery with a percutaneous intracoronary balloon, followed by reperfusion.Three days and 1 month after AMI, after 12 h fasting, 18F-FDG-PET-cMRI were performed by using standardized acquisition protocols (n = 30).Cardiac functional parameter, such as ejection fraction (EF), end-diastolic volume (EDV), infarct size, and mean tracer uptake of the infarcted area were quantitatively assessed.Six animals were euthanized after the 3-day 18F-FDG-PET-cMRI images to elaborate the differences in gene expression patterns in animals with perfusion-metabolic mismatch by using next generation sequencing (NGS) and pathway network analyses.Results: Eight (group Mismatch) of the 30 animals (group Match) with 1-month follow-up showed high 18F-FDG uptake in the infarcted area (perfusion-metabolism mismatch) at the 3-day 18F-FDG-PET-cMRI-LE images (Fig. 1).The animals in the Mismatch group had significantly lower EF at 3 days (34 ± 8.8 vs. 42 ± 3%) and at the 1-month follow-up (35.8 ± 6 vs. 43 ± 6.6%) and larger infarct size at day 3 (26.6 ± 6.6 vs. 22.1 ± 4.4%) and 1 month (28 ± 5.4 vs. 20.3 ± 4.3%) with higher EDV at 1 month.Mean tracer uptake of the infarcted area was significantly reduced in the Mismatch group at 1 month (56 ± 23.1 vs. 64.7 ± 13.2%), indicating enhanced severity and transmurality of the infarction.NGS revealed downregulation of the cholesterol metabolism pathway, and upregulation of carbohydrate derivative catabolism pathway with highly activated innate immune system and genes responsible for cytokine activation in the infarcted area 3 days post-AMI in the Mismatch group, which explains the paradox high 18F-FDG tracer uptake in the infarction zone.Accordingly, high energy demand of the severe hypoxic area led to "glucose steel phenomenon" at molecular level, subtracting the glucose (18F-FDG) from the normally perfused non-ischemic myocardial regions.Conclusions: Molecular glucose steel phenomenon leading to 18F-FDG perfusion-metabolism mismatch in the severe ischemic area early after AMI predict development of adverse remodeling of the heart.